Expanding a Galaxy object in the tag picker hung on "loading…": the browse
reply inlined every child's full attribute set (~152 KB), exceeding Akka's
128 KB remote frame, and remoting silently discarded the oversized reply.
Browse path (DataConnectionLayer):
- RealMxGatewayClient: navigation now uses BrowseChildren(include_attributes=
false) — child objects only — and an object's own attributes load lazily via
DiscoverHierarchy(root, max_depth=0) when it's expanded. Payload drops from
~152 KB/level to a few KB. Seam contract unchanged.
- DataConnectionActor.CapBrowseChildren: protocol-agnostic byte-budget cap
(~100 KB) on every BrowseNodeResult before it crosses the site→central
frame, OR-ing the adapter's own Truncated flag. Byte budget, not a count —
the only bound that holds regardless of NodeId/attribute-name length.
- RealOpcUaClient: requestedMaxReferencesPerNode 1000 → 500 to narrow the
window before the byte budget applies.
- Graceful gRPC Unimplemented handling → NotSupportedException →
BrowseFailureKind.NotBrowsable with an actionable message (older gateway
builds lacking BrowseChildren).
Picker UI (CentralUI):
- NodeBrowserDialog: modal-lg → modal-xl; new scoped .razor.css caps the tree
at 55vh with its own scrollbar so manual entry + Select/Cancel stay visible.
- Protocol-agnostic failure messages (was hardcoded "OPC UA …"); renamed the
leftover opcua-browser-tree class to node-browser-tree.
Tests: new frame-budget cap test + NotSupported=>NotBrowsable mapping test;
DCL suite 88/88. Doc: Component-DataConnectionLayer.md records the lazy
attribute-light browse and the frame-size guard.
- BrowseOpcUaNodeCommand: int DataConnectionId -> string ConnectionName
(site DataConnectionManagerActor indexes children by name; CentralUI
already has the connection name in scope via the dropdown — no extra
plumbing across the trust boundary).
- IOpcUaBrowseService / OpcUaBrowseService: parameter renamed accordingly.
- OpcUaBrowserDialog: collapse the duplicate ConnectionName parameters
(display label and routing key are the same string).
- Task 10: DataConnectionManagerActor forwards BrowseOpcUaNodeCommand to
its child by name (owns ConnectionNotFound); DataConnectionActor adds
the receive across all three lifecycle states (Connecting / Connected
/ Reconnecting) and maps adapter outcomes to BrowseFailureKind
(NotBrowsable / ConnectionNotConnected / Timeout / ServerError).
- Task 17: SetFailure in OpcUaBrowserDialog implements the full
BrowseFailureKind switch with friendly UI messages.
- Tests: DataConnectionManagerBrowseHandlerTests covers ConnectionNotFound,
NotBrowsable, success, and ConnectionNotConnectedException paths.
Joseph Doherty